Light emitting apparatus and method for manufacturing the same

ABSTRACT

The light emitting apparatus according to the invention having a thin film transistor and a light emitting element, comprises; a first inorganic insulation layer on the lower surface of a semiconductor layer, a second inorganic insulation layer on the upper surface of a gate electrode, a first organic insulation layer on the second inorganic insulation layer, a third inorganic insulation layer on the first organic insulation layer, a wiring layer extending on the third inorganic insulation layer, a second organic insulation layer overlapped with the end of the wiring layer and having an inclination angle of 35 to 45 degrees, a fourth inorganic insulation layer formed on the upper surface and side surface of the second organic insulation layer and having an opening over the wiring layer, a cathode layer formed in contact with the wiring layer and having side end overlapped with the fourth inorganic insulation layer, and an organic compound layer formed in contact with the cathode layer and the fourth inorganic insulation layer and comprising light emitting material, and an anode layer formed in contact with the organic compound layer comprising the light emitting material, wherein the third inorganic insulation layer and the fourth inorganic insulation layer are formed with silicon nitride or aluminum nitride.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light emitting apparatus comprising alight emitting element which emit fluorescent light or phosphorescentlight. In particular, the invention relates to a light emittingapparatus comprising an active element such as insulation gate typetransistor or a thin film transistor, and a light emitting elementcoupled thereto.

2. Description of the Related Art

A typical display apparatus utilizing liquid crystal uses a back lightor a front light for displaying images. A liquid crystal displayapparatus is employed as an image displaying unit in variouselectronics, but suffers a problem that it has a narrow angled field ofview. On the contrary, a display which uses light emitting elementsproviding electro-luminescence as a display unit has a wider angledfield of view as well as high level of visual recognition. Theseadvantages make the electro-luminescent display prospective for the nextgeneration.

In a light emitting element utilizing the electro-luminescence,electrons injected from a cathode and positive holes injected from ananode couple on a layer comprising light emitting material to formexcitons. Light is generated by the energy released when the excitonsmove back to the ground state. There are two types ofelectro-luminescence, i.e., fluorescent light and phosphorescent light,each which are considered as light emitted from the excitons in asinglet state (fluorescent light), and light emitted from the excitonsin a triplet state (phosphorescent light), respectively. The luminancefrom electro-luminescence ranges from thousands cd/m² to tens ofthousands cd/m², which makes it possible in principle to adopt theelectro-luminescence light emitting elements in a variety ofapplications including a display apparatus.

An example of a combination of a thin-film transistor (hereinafterreferred to as “TFT”) and a light emitting element is disclosed in theJapanese Patent Laid-Open No. JP-A-8-241047. In the constructiondisclosed in this JP-A-8-241047, an organic electro-luminescence layeris formed over a TFT comprising polycrystalline silicon, via aninsulation film comprising silicon dioxide. A passivasion layer having atapered end on the anode is positioned under the organicelectro-luminescence layer. The cathode is made from a material with awork function of 4 eV or less. An example of an applicable material isan alloy of metal such as silver or aluminum, and magnesium.

Problem to be Solved

Known methods for manufacturing the organic electro-luminescence layerinclude vacuum evaporation, printing, and spin coating. However, it isdifficult to form determined patterns on the organicelectro-luminescence layer by photolithography technique as used in thesemiconductor element manufacturing. In order to arrange the lightemitting elements in a matrix to make a display screen, a specialconstruction is necessary in which each pixel is partitioned withinsulation material, as disclosed in the above JP-A-8-241047.

In the first place, an organic compound used for the light emittingelements, and an alkali metal or an alkali earth metal used for anelectrode are degraded by reactions with water and oxygen. This preventspractical application of the light emitting apparatus comprising thelight emitting elements.

The organic light emitting element deteriorates due to following sixfactors; (1) change in the chemical characteristics of the organiccompound (2) change in the structure, or deterioration by fusion, of theorganic compounds by heat generated at operating, (3) destruction ofinsulation due to macro-level defect, (4) deterioration of the interfacebetween the electrodes, or the electrode and the organic compound layercomprising the light emitting element, (5) deterioration caused by thechange in bonding state or crystallization of the organic compound dueto amorphous form, and (6) irreversible destruction caused by stress ordistortion due to the structure of the elements.

The deterioration by the factor (1) is caused by chemical changeincurred by excitation, or gas which is corrosive against the organiccompounds or moisture. The deterioration by the factor (2) and (3) iscaused by the operation of the organic light emitting element. Heat isinevitably generated when current in the element is converted into Jouleheat. When the organic compound has low melting point or glasstransition temperature, the electric field concentrate around pinholesor cracks and dielectric breakdowns occur. The deterioration by thefactors (4) and (5) is inevitable even when the element is stored atambient temperature. The deterioration by the factor (4) is known asdark spots, which are generated by the oxidation of the cathode or thereaction to moisture. For deterioration by the factor (5), all theorganic compounds used in the organic light emitting element areamorphous, so that they will be inevitably crystallized in a long periodby heat for example. Almost no organic compound can keep its amorphousstructure for a long time. For deterioration by the factor (6), a defectsuch as a crack or a break of the coating due to distortion may developby the difference in thermal expansion coefficient between components.Furthermore, the crack or the break may lead to a progressive defectsuch as dark spots.

The advance in sealing techniques has fairly mitigated the problem ofdark spots. However in practice, the deterioration is caused by two ormore of the above factors, which makes it difficult to take effectivepreventive measure. In typical sealing method, the organic lightemitting element formed over a substrate is sealed with sealant, anddrying agent such as barium oxide is applied in the spaces.Unfortunately, conventional preventive measures have failed to suppressthe deterioration of the light emitting apparatus to an acceptablelevel.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the above problems inorder to improve the reliability of a light emitting apparatuscomprising TFTs and organic light emitting elements.

For this purpose, according to the present invention, a light emittingapparatus with pixels consisting of electrically connected TFTs andlight emitting elements has a construction wherein the light emittingelements are formed by laminating an anode layer, a cathode layer, andan interposed layer containing light emitting material, surrounding theupper surface, the lower surface and the side surface of the lightemitting element with an inorganic insulation layer, and the anodelayer, the cathode layer and the layer containing light emittingmaterial respectively contact with the surrounding inorganic insulationlayer. The inorganic insulation layer is formed of silicon nitride oroxynitride of silicon such as a silicon nitride film or a siliconoxynitride film, or, nitride or oxynitride of aluminum such as aluminumnitride or aluminum oxynitride. More preferably, the silicon nitridefilm formed by radio frequency sputtering (RF sputtering) with frequencyranging from 13.56 MHz to 120 MHz and having silicon as a target isapplied.

The silicon nitride film manufactured by the RF sputtering has improvedeffect of blocking the external impurities and an effect of suppressingthe deterioration of the light emitting element by satisfying one of thefollowing conditions; (1) a silicon nitride film with etching rate of 9nm/min or less (preferably, 0.5 to 3.5 nm/min or less), (2) hydrogenconcentration of 1×10²¹ atoms/cm⁻³ or less (preferably 5×10²⁰ atoms/cm³or less), (3) hydrogen concentration of 1×10²¹atoms/cm³ or less(preferably 5×10²⁰ atoms/cm³ or less), and oxygen concentration from5×10¹⁸ to 5×10²¹ atoms/cm³ (preferably 1×10 to atoms/cm³), (4) etchingrate of 9 nm/min or less (preferably, 0.5 to 3.5 nm/min or less), andhydrogen concentration of 1×10²¹ atoms/cm³ or less (preferably 5×10²⁰atoms/cm or less), or (5) etching rate of 9 nm/min or less (preferably,0.5 to 3.5 nm/min or less), hydrogen concentration of 1×10²¹ atoms/cm3or less (preferably 5×10²⁰ atoms/cm³ or less), and oxygen concentrationfrom 5×10¹⁸ to 5×10²¹ atoms/cm³ (preferably 1×10¹⁹ to 1×10²¹ atoms/cm³).

In a construction wherein a display screen has light emitting elementsarranged in matrix, the most preferable construction of an insulationlayer to partition the each pixel comprises a positive-type or anegative-type photosensitive organic resin material and has a curvatureradius of 0.2 to 2 μm or continuously varying curvature radiuses withinthe above range at the end of the patterns, and a tapered surface withan inclination angle from 10 to 75 degrees, preferably from 35 to 45degrees. The construction of a pixel in the light emitting apparatusaccording to the invention can mitigate the stress on the electrode endsof the pixel and suppress the deterioration of the light emittingelement, by forming an insulation layer which covers ends of theindividual electrode (either anode or cathode) of each pixel connectingto the TFT to partition each pixel, and by forming a layer containingthe light emitting material, and one of the anode layer or the cathodelayer, from over the pixel electrode to over the insulation layer.

The construction of a light emitting apparatus according to theinvention will be described below.

A light emitting apparatus comprising a TFT having a semiconductorlayer, a gate insulation film and a gate electrode, and a light emittingelement having an organic compound layer containing light emittingmaterial between a cathode layer and an anode layer, comprises,

-   -   a first inorganic insulation layer under the semiconductor        layer,    -   a second inorganic insulation layer on the gate electrode,    -   a first organic insulation layer on the second inorganic        insulation layer,    -   a third inorganic insulation layer on the first organic        insulation layer,    -   a wiring layer extending on the third inorganic insulation        layer,    -   a second organic insulation layer overlapping with the end of        the wiring layer, the second organic insulation layer having an        inclination angle of 35 to 45 degrees,    -   a fourth inorganic insulation layer formed on the upper surface        and the side surface of the second organic insulation layer, the        fourth inorganic insulation layer having an opening over the        wiring layer,    -   a cathode layer formed in contact with the wiring layer and        having an end overlapping with the fourth inorganic insulation        layer,    -   an organic compound layer formed in contact with the cathode        layer and the fourth inorganic insulation layer, the organic        compound layer containing the light emitting material, and    -   an anode layer formed in contact with the organic compound layer        containing the light emitting material,    -   wherein;    -   the third inorganic insulation layer and the fourth inorganic        insulation layer comprise silicon nitride or aluminum nitride.

A light emitting apparatus comprising a pixel section having a TFThaving a semiconductor layer, a gate insulation film and a gateelectrode, and a light emitting element including an organic compoundlayer containing light emitting material between an anode layer and acathode layer, and a driving circuit section formed from a thin filmtransistor having a semiconductor layer, a gate insulation film and agate electrode, the driving circuit section being formed in theperipheral region of the pixel section, comprises;

-   -   a first inorganic insulation layer under the semiconductor        layer,    -   a second inorganic insulation layer on the gate electrode,    -   a first organic insulation layer on the second inorganic        insulation layer,    -   a third inorganic insulation layer on the first organic        insulation layer,    -   a wiring layer extending on the third inorganic insulation        layer,    -   a second organic insulation layer overlapping with the end of        the wiring layer, the second organic insulation layer having an        inclination angle of 35 to 45 degrees,    -   a fourth inorganic insulation layer formed on the upper surface        and the side surface of the second organic insulation layer, the        fourth inorganic insulation layer having an opening over the        wiring layer,    -   a cathode layer formed in contact with the wiring layer, the        cathode layer having an end overlapping with the fourth        inorganic insulation layer,    -   an organic compound layer formed in contact with the cathode        layer and the fourth inorganic insulation layer, the organic        compound layer containing the light emitting material, and,    -   an anode layer formed in contact with the organic compound layer        containing the light emitting material,    -   wherein;    -   the third inorganic insulation layer and the fourth inorganic        insulation layer comprise silicon nitride or aluminum nitride,    -   seal patterns are formed on the fourth inorganic insulation        layer, and    -   some or all of the seal patterns overlap with the driving        circuit section.

The cathode layer may have the fifth inorganic insulation layer thereon,which is formed of nitride of silicon or aluminum.

The third to the fifth inorganic insulation layers have the abovementioned etching characteristics, and hydrogen concentration and oxygenconcentration in the above range. By reducing the density of N—H bond,Si—H bond and the Si—O bond, the construction according to the inventioncan improve thermal stability of a film and make a fine film.

A light emitting apparatus comprising a pixel section having a TFThaving a semiconductor layer, a gate insulation film and agateelectrode, and a light emitting element including an organic compoundlayer containing light emitting material between an anode layer and acathode layer, and a driving circuit section formed from a TFT having asemiconductor layer, a gate insulation film and a gate electrode, thedriving circuit section being formed in the peripheral region of thepixel section, wherein;

-   -   a barrier layer formed from an organic insulation layer on the        pixel section extends over the driving circuit section,    -   an inorganic insulation layer comprising silicon nitride or        aluminum nitride is formed on the upper surface and the side        surface of the barrier layer,    -   seal patterns are formed on the inorganic insulation layer,    -   some or all of the seal patterns overlap with the driving        circuit section, and    -   a connection between the anode layer and the wiring formed under        the anode layer is provided inside of the seal patterns.

A light emitting apparatus comprising a pixel section having a first TFThaving a semiconductor layer, a gate insulation film and a gateelectrode, and alight emitting element including an organic compoundlayer containing light emitting material between an anode layer and acathode layer, and a driving circuit section formed from a second TFThaving a semiconductor layer, a gate insulation film and a gateelectrode, the driving circuit section being formed in the peripheralregion of the pixel section, wherein;

-   -   a barrier layer formed from an organic insulation layer on the        pixel section extends over the driving circuit section,    -   an inorganic insulation layer comprising silicon nitride or        aluminum nitride is formed on the upper surface and the side        surface of the barrier layer,    -   seal patterns are formed on the inorganic insulation layer,    -   the first TFT is formed inside of the seal patterns,    -   all or some of the second TFT overlap with the seal patterns,        and,    -   a connection between the anode layer and the wiring formed under        the anode layer is provided inside of the seal patterns.

The inorganic insulation layer comprises silicon nitride manufactured bythe RF sputtering method, and has the above mentioned etchingcharacteristics, and hydrogen concentration and oxygen concentration inthe above range.

The another aspect of the invention provides a method to manufacture alight emitting apparatus, as described below.

A method for manufacturing a light emitting apparatus comprising a pixelsection having a TFT having a semiconductor layer, a gate insulationfilm and a gate electrode, and a light emitting element including anorganic compound layer containing light emitting material between ananode layer and a cathode layer, and a driving circuit section formedfrom a thin film transistor having a semiconductor layer, a gateinsulation film and a gate electrode, the driving circuit section beingformed in the peripheral region of the pixel section, comprises stepsof;

-   -   forming a first inorganic insulation layer on a substrate,        forming a semiconductor layer comprising crystalline silicon on        the first inorganic insulation layer,    -   forming a gate insulation film on the semiconductor layer and a        gate electrode on the gate insulation film,    -   forming a second inorganic insulation layer on the gate        electrode,    -   forming a first organic insulation layer on the second inorganic        insulation layer,    -   forming a third inorganic insulation layer on the second organic        insulation layer,    -   forming a wiring layer in contact with the third inorganic        insulation layer,    -   forming a second organic insulation layer overlapping with the        end of the wiring layer, the second organic insulation layer        having an inclination angle of 35 to 45 degrees,    -   forming a fourth inorganic insulation layer on the upper surface        and side surface of the second organic insulation layer, the        fourth inorganic insulation layer having an opening over the        wiring layer,    -   forming a cathode layer in contact with the wiring layer, the        cathode layer having an end overlapping with the fourth        insulation layer,    -   forming an organic compound layer containing the light emitting        material in contact with the cathode layer and the fourth        inorganic insulation layer, and,    -   forming an anode layer in contact with the organic compound        layer containing the light emitting material, wherein,    -   the third inorganic insulation layer and the fourth inorganic        insulation layer comprise silicon nitride or aluminum nitride        formed by RF sputtering method.

A method for manufacturing a light emitting apparatus comprising a pixelsection having a TFT having a semiconductor layer, a gate insulationfilm and a gate electrode, and a light emitting element including anorganic compound layer containing light emitting material between ananode layer and a cathode layer, and a driving circuit section formedfrom a TFT having a semiconductor layer, a gate insulation film and agate electrode, the driving circuit section being formed in theperipheral region of the pixel section, comprises steps of;

-   -   forming a first inorganic insulation layer on a substrate,    -   forming a semiconductor layer comprising crystalline silicon on        the first inorganic insulation layer,    -   forming a gate insulation film on the semiconductor layer and a        gate electrode on the gate insulation film,    -   forming a second inorganic insulation layer on the gate        electrode,    -   forming a first organic insulation layer on the second inorganic        insulation layer,    -   forming a third inorganic insulation layer on the second organic        insulation layer,    -   forming a wiring layer in contact with the third inorganic        insulation layer,    -   forming a second organic insulation layer overlapping with the        end of the wiring layer, the second organic insulation layer        having an inclination angle of 35 to 45 degrees,    -   forming a fourth inorganic insulation layer on the upper surface        and side surface of the second organic insulation layer, the        fourth inorganic insulation layer having an opening over the        wiring layer,    -   forming a cathode layer in contact with the wiring layer, the        cathode layer having an end overlapping with the fourth        insulation layer,    -   forming an organic compound layer containing the light emitting        material formed in contact with the cathode layer and the fourth        inorganic insulation layer,    -   forming an anode layer in contact with the organic compound        layer containing the light emitting material,    -   forming seal patterns on the fourth insulation layer at a        position in which some or all of the seal patterns overlap with        the driving circuit section, and,    -   adhering a sealing plate in alignment with the seal patterns,    -   wherein,    -   the third inorganic insulation layer and the fourth inorganic        insulation layer comprise silicon nitride or aluminum nitride        formed by RF sputtering method.

In the above construction according to the invention, the third and thefourth inorganic insulation layers comprise silicon nitride by the RFsputtering method using only nitrogen as sputtering gas and havingsilicon as a target. The third inorganic insulation layer is formedafter formation of the first organic insulation layer, by heating anddehydrating under reduced pressure, while the reduced pressure ismaintained. The fourth inorganic insulation layer is formed afterformation of the second organic insulation layer, by heating anddehydrating under reduced pressure, while the reduced pressure ismaintained.

The light emitting apparatus herein refers to the apparatus which useselectro-luminescence for emitting light, in general. The light emittingapparatus includes a TFT substrate in which circuitry is formed from TFTon a substrate for light emission, an EL panel which incorporates thelight emitting elements formed with electro-luminescence material on aTFT substrate, and an EL module which incorporates external circuitryinto an EL panel. The light emitting apparatus according to theinvention can be incorporated in a variety of electronics such as amobile telephone, a personal computer and a television receiver.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cross-sectional view which illustrates the construction ofthe light emitting apparatus according to the invention.

FIG. 2 is a top view which illustrates the construction of the pixelsection of the light emitting apparatus according to the invention.

FIG. 3 is a cross-sectional view which illustrates the construction ofthe pixel section of the light emitting apparatus according to theinvention.

FIG. 4 is another cross-sectional view which illustrates theconstruction of the pixel section of the light emitting apparatusaccording to the invention.

FIG. 5 is an outside view of a substrate comprising components of thelight emitting apparatus according to the invention.

FIG. 6 is a view which illustrates a substrate constituting a lightemitting apparatus formed on a mother glass, and its separation.

FIGS. 7A to 7C show a construction of the input terminal in the lightemitting apparatus according to the invention.

FIGS. 8A to 8D are cross-sectional views which illustrate manufacturingprocesses of the light emitting apparatus according to the invention.

FIGS. 9A to 9C are cross-sectional views which illustrate manufacturingprocesses of the light emitting apparatus according to the invention.

FIGS. 10A to 10C are cross-sectional views which illustratemanufacturing processes of the light emitting apparatus according to theinvention.

FIGS. 11A and 11B are cross-sectional views which illustratemanufacturing processes of the light emitting apparatus according to theinvention.

FIG. 12 is a top view which illustrates manufacturing processes of thelight emitting apparatus according to the invention.

FIG. 13 is a top view which illustrates manufacturing processes of thelight emitting apparatus according to the invention.

FIG. 14 is a cross-sectional view which illustrates a construction ofthe light emitting apparatus according to the invention.

FIG. 15 is a top view which illustrates a construction of the pixelsection of the light emitting apparatus according to the invention.

FIG. 16 is a top view which illustrates a construction of the pixelsection of the light emitting apparatus according to the invention.

FIG. 17 is a circuit diagram equivalent to a pixel.

FIG. 18 shows an example of a process to manufacture semiconductorlayers to be adopted in the TFT constituting the light emittingapparatus according to the invention.

FIG. 19 shows an example of a process to manufacture semiconductorlayers to be adopted in the TFT constituting the light emittingapparatus according to the invention.

FIGS. 20A to 20C show an example of a process to manufacturesemiconductor layers to be adopted in the TFT constituting the lightemitting apparatus according to the invention.

FIG. 21 shows an example of a process to manufacture semiconductorlayers to be adopted in the TFT constituting the light emittingapparatus according to the invention.

FIGS. 22A to 22G are views which show applications of the invention.

FIGS. 23A and 23B show one construction of the EL module.

FIG. 24 is a graph which shows SIMS measurement data (secondary ion massspectrometry) of the silicon nitride film.

FIG. 25 is a graph which shows FT-IR measurement data of the siliconnitride film.

FIG. 26 is a graph which shows measurement of the transmittance of thesilicon nitride film.

FIG. 27 is a graph which shows the C-V characteristics before and afterthe BT stress test of the MOS construction.

FIGS. 28A and 28B are graphs which show the C-V characteristics beforeand after the BT stress test of the MOS construction.

FIGS. 29A and 29B are views which illustrate the MOS construction.

FIG. 30 is a view which illustrates a sputtering apparatus.

FIGS. 31A and 31B are cross-sectional views which illustrate theconstruction of the pixel section of the light emitting apparatusaccording to the invention.

FIGS. 32A and 32B are cross-sectional views which illustrate theconstruction of the pixel section of the light emitting apparatusaccording to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The embodiments of the invention will be described with reference to theaccompanied drawings. Common components among several drawings have samereference numerals.

FIG. 1 shows a construction of a light emitting apparatus of an activematrix driving method according to the present invention. The TFTs areprovided in a pixel section 302 and a driving circuit section 301 formedaround the pixel section 302. Either amorphous silicon, polysilicon, orsingle crystal silicon is applicable for the semiconductor layer whichforms the channel forming region of the TFT. For switching purpose, theTFT may be formed with organic semiconductor.

The substrate 101 comprises a glass substrate or an organic resinsubstrate. The organic resin has lighter weight than the glass, which isadvantageous to reduce the weight of the light emitting apparatus as awhole. Organic resin such as polyimide, polyethylene terephthalate(PET), polyethylene naphthalate (PEN), polyether sulfone (PES), andaramid is applicable to manufacture the light emitting apparatus.Borosilicate glass which is known as no-alkali glass containing lessamount of alkali metal element is preferred to be used as a glasssubstrate. The thickness of the glass substrate may be 0.5 to 1.1 mm,however, if it is necessary to reduce the weight of the apparatus, thethickness should be reduced. It is desirable to employ a glass materialwith small specific density such as 2.37 g/cm³ to furthermore reduce theweight.

In the construction shown in FIG. 1, a n-channel type TFT 303 and ap-channel type TFT 304 are formed in the driving circuit section 301,and a first TFT 305 and a fourth TFT 306 formed with n-channel type TFTare formed in the pixel section 302. The fourth TFT 306 connects to acathode 126 of a light emitting element 309.

These TFT comprises semiconductor layers 103 to 106, a gate insulationfilm 108, and gate electrodes 110 to 113 on a first inorganic insulationlayer 102 formed of silicon nitride or silicon oxynitride. A secondinorganic insulation layer 114 formed of silicon nitride or siliconoxynitride containing hydrogen is formed on the gate electrode. Thesecond inorganic insulation layer in combination with the firstinorganic insulation layer 102 serves as a protective film whichprevents contamination of the semiconductor layers caused by diffusionof impurities such as moisture or metal into the semiconductor layer.

A first organic insulation layer 115 of 0.5 to 1 μm thickness formed ofone of polyimid, polyamide, polyimidamide, acrylic, BCB(benzocyclobutene) is formed as a planarizing layer on the secondinorganic insulation layer 114. The first organic insulation layer 115is formed by spin coating one of the above organic compounds, thenapplying calcination. The organic insulation material is hygroscopic andabsorbs and occludes moisture. When the occluded moisture is released,oxygen is supplied to the organic compounds included in the lightemitting element formed over the organic insulation layer, whichdeteriorates the organic light emitting element. To prevent theocclusion and the release of moisture, a third inorganic insulationlayer 116 of 50 to 200 nm thickness is formed on the first organicinsulation layer 115. The third inorganic insulation layer 116 must be afine film in order to adhere to the underlining layer more securely toprovide barrier. The layer 116 is formed preferably by the sputtering ofan inorganic insulation material selected from silicon nitride, siliconoxynitride, aluminum oxynitride and aluminum nitride. Wirings 117 to 125are formed after the formation of the third inorganic insulation layer116.

The light emitting element 309 is formed on an anode layer 131, thecathode layer 126 comprising alkali metal or alkali earth metal, and aninterposing organic compound layer 130 containing a light emittingmaterial. The organic compound layer 130 containing the light emittingmaterial is formed by laminating one or more layers. Each layer is namedaccording to its purpose and function; a positive hole injection layer,a positive hole transferring layer, a light emitting layer, an electronstransferring layer and an electrons injection layer. These layers can beformed of low molecular weight organic compounds, middle molecularweight organic compounds, high molecular weight organic compounds, orcombination of two of the above compounds appropriately. Also, a mixedlayer comprising mixture of the electron transferring material and thepositive hole transferring material, or a mixed connection forming mixedregion between the interface of them can be made.

This organic light emitting element 309 is formed on the third inorganicinsulation layer 116. The light emitting apparatus having a constructionto emit light in the direction opposite to the substrate 101 causes thecathode layer 126 of the light emitting element 309 to contact to thewiring 123 formed on the third inorganic insulation layer 116. Thecathode layer 126 is formed of an alkali metal or an alkali earth metalhaving smaller work function, such as magnesium (Mg), lithium (Li) orcalcium (Ca). Preferably, an electrode comprising MgAg (a mixture of Mgand Ag with ratio of 10:1) may be used. Other materials suitable to theelctrode include MgAgAl, LiAl and LiFAl. The combination of fluoride ofan alkali metal an or alkali earth metal, and a low resistance metalsuch as alminum can be used, as well.

A second organic insulation layer (partition layer) 128 which separateseach pixel is formed of one of polyimide, polyamide, polyimideamide,acrylic and benzocyclobutene (BCB). Thermosetting material orphoto-curing material is applicable. The second organic insulation layer(partition layer) 128 is formed by applying the one of the above organicinsulation material with thickness of 0.5 to 2 μm to cover all surface.Then, an opening fitting to the cathode layer 126 is formed. At thistime, the opening is formed so as to cover the end of the wiring 123 andthe inclination angle on its side is 35 to 45 degrees. The secondorganic insulation layer (partition layer) 128 extends not only over thepixel section 302 but also over the driving circuit section 301 andcovers the wiring 117 to 124, thus, it also serves as an interlayerinsulation film between layers.

The organic insulation material is hygroscopic and absorbs and occludesmoisture. When the occluded moisture is released, the moisture issupplied to the organic compounds of the light emitting element 309,which deteriorates the organic light emitting element. To prevent theocclusion and the release of moisture, a fourth inorganic insulationlayer 129 of 10 to 100 nm thickness is formed on the second organicinsulation layer 128. The fourth inorganic insulation layer 129 isformed of an inorganic insulation material comprising nitrides.Particularly, it is formed with an inorganic insulation materialselected from silicon nitride, aluminum nitride and aluminum oxynitride.The fourth inorganic insulation layer 129 is formed so as to cover theupper surface and side surface of the second organic insulation layer128, and its end overlapping with the wiring 123 is tapered.

The anode layer 131 is formed across a plurality of pixels as a commonelectrode, and connects to the wiring 120 at a connection region 310positioned outside of the pixel section 302 or between the pixel section302 and the driving circuit section 301, then leads to an externalterminal. ITO layer (indium oxide, tin) layer is formed as the anodelayer 131. ITO may be added with zinc oxide or gallium for planarizing,or reducing the resistance.

On the anode layer 131, a fifth inorganic insulation layer 132 may beformed of one of silicon nitride, diamond-like-carbon (DLC), aluminumoxynitride, aluminum oxide or aluminum nitride. It is known that the DLCfilm has high gas barrier characteristic against oxygen, CO, CO₂ andH₂O. It is desirable to form the fifth inorganic insulation layer 132 insuccession after the formation of the anodes 131 without exposing thesubstrate to the atmosphere. A buffer layer made of silicon nitride maybe provided under the fifth inorganic insulation layer 132 in order toimprove adhesion.

Although not shown in the figure, a sixth inorganic insulation layer of0.5 to 5 nm thickness which allows flow of a tunnel current may beformed between the cathode layer 126 and the organic compound layer 130containing light emitting material. The sixth inorganic insulation layerhas an effect to prevent short circuit caused by any irregularity on thesurface of the anode, and an effect to prevent alkali metal used for thecathode, or the like, from diffusing to the lower layer.

The second organic insulation layer 128 formed over the pixel section302 extends to the driving circuit section 301, and seal patterns 133are formed on the fourth inorganic insulation layer 129 formed on thesecond organic insulation layer 128. Some or all of the seal patterns133 may overlap with the driving circuit section 301 and the wiring 117which connects the driving circuit section 301 and the input terminal,which reduces the area of the frame region (peripheral region of thepixel section) of the light emitting apparatus. The light from the lightemitting element 309 is emitted through this sealing plate.

A sealing plate 134 is secured via the sealing patterns 133. An organicresin including polyimide, polyethylene terephthalate (PET),polyethylene naphthalate (PEN), polyethersulfone (PES) and aramid aswell as a glass substrate can be used for the sealing plate 134. Thesealing plate made of an organic resin may be flexible and have 30 to120 μm thickness. This prevents scratch on the surface of the sealingplate. The surface of the sealing plate may be coated with an inorganicinsulation material such as DLC and silicon nitride as a gas barrierlayer. One exemplary material for the seal patterns is epoxy adhesive.The side surface of the seal patterns may be coated with a filmcomprising inorganic insulation material, which prevents vapor frompenetrating from the side surface.

In FIG. 1, the first TFT 305 has a multi-gate construction, and providedwith a light doped drain (LDD) to reduce the off current. A LDDoverlapping with the gate electrode is provided on the fourth TFT 306. ATFT made of poly-crystalline silicon is prone to deteriorate caused by ahot-carrier effect because it has a high operating rate. Therefore, asshown in FIG. 1, it is highly advantageous to form TFTs having differentconstruction for different function in the pixel (switching TFT withsufficiently low off current and current control TFT durable to hotcarrier injection), in order to manufacture a display apparatus havinghigh reliability and good displaying performance (high operatingperformance).

The top view of one pixel in the pixel section provided with the aboveTFT is shown in FIG. 2. In order to illustrate the arrangement of eachTFT clearly, the patterns of the light emitting element 309, the secondorganic insulation layer 128 and the fourth inorganic insulation layer129 are not shown in FIG. 2. One pixel contains the first TFT 305, asecond TFT 311, a third TFT 312, the fourth TFT 306 and a capacitysection 307. FIG. 17 schematically shows a circuit equivalent to theconstruction shown in FIG. 2. FIG. 1 shows the cross section across theline A-A′ of FIG. 2. FIG. 3 shows the cross section across the lineB-B′, and FIG. 4 shows the cross section across the line C-C′, of FIG.2.

One exemplary construction of the second organic insulation layer 128and the fourth inorganic insulation layer 129 in the pixel section isshown in FIG. 15, in which both of them cover the periphery of thecathode layer 126. In another exemplary construction shown in FIG. 16,the second organic insulation later 128 may cover only two sides of thecathode layer 126, while the fourth inorganic insulation layer 129 maycover all sides of the cathode layer 126.

Although not shown in FIG. 1, the driving circuit section 301 hasdifferent circuitry for the gate signal driving circuit and the datasignal driving circuit. The wirings 118 and 119 are connected to then-channel type TFT 303 and the p-channel type TFT 304, respectively, andthese TFTs, in turn, can be used to form a shift register, a latchcircuit or a buffer circuit.

An input terminal 308 is formed from a wiring formed from the same layeras the gate electrode, or a wiring formed on the third inorganicinsulation layer 116. FIG. 1 shows an example of the input terminal 308formed from the same layer as the gate electrode, that is, the inputterminal 308 is formed from conducting layers 109 and 127. Theconducting layer 127 is formed of oxide conductive material, at the timewhen the anode layer 131 is formed. In practice, the part exposed to thesurface is covered with the oxide conductive material to prevent theincrease of surface resistance due to oxidation. FIG. 7 is a detailedillustration of the input terminal 308. FIG. 7A shows the top view, andFIGS. 7B and 7C show cross-sectional views across the line D-D′ andE-E′, respectively. The reference numerals in FIG. 7 are in common withthose in FIG. 1.

As shown in FIG. 1, the first inorganic insulation layer 102 and thesecond inorganic insulation layer 114 are formed so as to sandwich thesemiconductor layers 105 and 106. On the other hand, the organic lightemitting element 309 is surrounded by the third inorganic insulationlayer 116, the fifth inorganic insulation layer 132 and the fourthinorganic insulation layer 129. In other words, the semiconductor layersof the TFT and light emitting elements are coated with the inorganicinsulation layers, respectively. The inorganic insulation layers aremade from films of silicon nitride or silicon oxynitride, which forms abarrier against vapor and ionic impurities.

The possible source of an alkali metal such as sodium which contaminatesthe first TFT 305 and the fourth TFT 306 includes the substrate 101 andthe organic light emitting element 309. In order to prevent thecontamination from them, the first TFT 305 and the fourth TFT 306 aresurrounded by the first inorganic insulation layer 102 and the secondinorganic insulation layer 114. As the organic light emitting element309 suffers the severest damage from oxygen and moisture, the thirdinorganic insulation layer 116, the fourth inorganic insulation layer129, and the fifth inorganic insulation layer 132 are formed withinorganic insulation materials to prevent the contamination by oxygen ormoisture. Also, these inorganic insulation layer serves to prevent thealkali metal element of the organic light emitting element 309 fromdiffusing to other sections.

FIG. 5 shows an outside view of a substrate comprising components of thelight emitting apparatus illustrated in FIGS. 1 to 4. The substrate 101comprises the pixel section 302, a gate signal driving circuits 301 aand 302 b, a data signal driving circuit 301 c, the connection 310 tothe anode layer, the input/output terminal 308 and wiring or a group ofwirings 117. The seal patterns 133 are provided so that the part or allof the patterns 133 overlap with the gate signal driving circuits 301 aand 301 b, data signal driving circuit 301 c and the wiring or the groupof wirings 117 which connects these driving circuit sections to theinput terminal, in order to reduce the area of the frame region(peripheral of the pixel section) of the light emitting apparatus. Theanode layer formed of ITO may have high resistivity, therefore, althoughFIG. 5 shows only one connection 310 to the anode layer, more than oneconnections 310 maybe provided on the other region around the pixelsection 302.

As shown in FIG. 6, a plurality of the substrates (101 a to 101 d)having above construction are provided on a mother glass 201, andseparated along cutting lines 202 after the formation of one of thefourth inorganic insulation layer, the cathode layer, the fifthinorganic insulation layer or the sealing plate. The substrates areseparated with a diamond cutter or a laser cutter. In order to make theseparating process easier, the third to the fifth inorganic insulationlayers and the first and the second organic insulation layers arepreferably removed along the cutting lines 202.

As described, a TFT and alight emitting element are combined to form apixel section to complete a light emitting apparatus. In the lightemitting apparatus thus manufactured, driving circuits can be formed onthe same substrate by using TFTs as the pixel section. As shown in FIG.1, by surrounding the upper surface and the lower surface of thesemiconductor film, the gate insulation film and the gate electrode,which are major components of a TFT, with blocking layers and theprotective films comprising silicon nitride or silicon oxynitride, thisconstruction prevents these components from being contaminated by analkali metal and an organic material. The organic light emittingelement, in turn, contains the alkali metal in part, and surrounded by aprotective film comprising one of silicon nitride, silicon oxynitride,or DLC, and a gas barrier layer comprising an insulation film mainlyconsisting of silicon nitride or carbon, so that this constructionprevents the penetration of oxygen or moisture from the outside.

The film comprising silicon nitride used for the inorganic insulationlayers in this embodiment (silicon nitride film) is a highly fine filmformed by the RF sputtering, according to the processing conditionsshown in the table 1 (A typical example is illustrated). “RFSP-SiN” inthe table indicates a silicon nitride film formed by the RF sputtering.“T/S” is the distance between the target and the substrate. TABLE 1RFSP-SiN processing condition representative processing conditionexample comments gas N₂ or (noble gas)/N₂ Ar/N₂ each purity is 4 N ormore gas flow ratio N₂: 30˜100%, noble gas: 0˜70% Ar:N₂ = 20:20 noblegas may be (sccm) introduced as gas for heating form the backside of asubstrate pressure (Pa) 0.1˜1.5 0.8 flequency (MHz) 13˜40 13.56 power(W/cm²)  5˜20 16.5 substrate RT (Room Temperature) ˜350 200 temperature(° C.) target material material carved out of Si(1˜10 Ωcm) singlecrystalline Si ingot T/S (mm)  40˜200 60 back-pressure(Pa) 1 × 10⁻³ orless (preferably 3 × 10⁻⁵ using turbo-molecular 3 × 10⁻⁵ or less) pumpor cryopump

Ar is introduced as sputtering gas to be sprayed on the back surface ofthe substrate to heat the same. The sprayed Ar is ultimately mixed withN₂ for sputtering. The values shown in the table 1 for forming a filmare only exemplary values. As long as the physical parameters of theresulting SiN film fall in the range of the physical parameters shown inthe table 4 (shown later), these conditions can be modifiedappropriately by the operator.

Next, a schematic view of a sputtering apparatus used to form a siliconnitride film by the above RF sputtering will be shown in FIG. 30. InFIG. 30, 30 is a chamber wall, 31 is a movable magnet for formingmagnetic field, 32 is a single crystal silicon target, 33 is aprotective shutter, 34 is a substrate to be processed, 36 a and 36 b areheaters, 37 is a substrate chuck device, 38 is an antitack plate and 39is a valve (conductance valve or main valve). The chamber wall 30 isprovided with gas intake tubes 40 and 41 which introduce N₂ (or mix gasof N₂ and inert gas), and inert gas, respectively.

Table 2 shows conditions to form a silicon nitride film formed by theconventional plasma CVD method, for reference. “PCVD-SiN” in the tablerefers to a silicon nitride film formed by the plasma CVD method. TABLE2 plasma CVD condition PCVD-SiN gas SiH₄/NH₃/N₂/H₂ gas flow ratio (sccm)SiH₄:NH3:N2:H2 = 30:240:300:60 pressure (Pa) 159 frequency (MHz) 13.56power (W/cm²) 0.35 substrate temperature (° C.) 325

Table 3 shows the the representative values of physical characteristics(physical parameters) of the silicon nitride film formed under theconditions in the table 1, and that formed under the conditions in thetable 2. The differences between “RFSP-SiN (No. 1)” and“RFSP-SiN (No.2)” are attributable to the difference between the film formingapparatuses, and do not impair the function of a silicon nitride film asa barrier film according to the invention. The internal stress may becompressive or tensile, and the sign of the numerical value changesaccordingly, but the table shows only the absolute value. TABLE 3comparison between representative SiN physical parameters SiN preparedby the condition referring to the SiN prepared by the conditionpreparing referring to the preparing condition in condition in Table. 1Table 2. parameter RFSP-SiN (No. 1) RFSP-SiN (No. 2) PCVD-SiN filmcomments specific inductive 7.02˜9.30 ←   ˜7 capacity refractive index1.91˜2.13 ← 2.0˜2.1 Wavelength of irradiated light is 632.8 nm internalstress 4.17 × 10⁸ ← 9.11 × 10⁸ (dyn/cm²) etching rate 0.77˜1.31 1˜8.6  ˜30 LAL500, 20° C. (nm/min) Si concentration 37.3 51.5 35.0 RBS(atomic %) N concentration 55.9 48.5 45.0 RBS (atomic %) H concentration  4 × 10²⁰ —   1 × 10²² SIMS (atoms/cm³) O concentration   8 × 10²⁰ —  3 × 10¹⁸ SIMS (stoms/cm³) C concentration   1 × 10¹⁹ —   4 × 10¹⁷ SIMS(atoms/cm³)

As shown in the table 3, the common characteristics in the RFSP-SiN(No. 1) and the RFSP-SiN (No. 2) are lower etching rate (the etchingrate of the etching with LAL 500 at 20° C., ditto), and lower hydrogenconcentration compared to that of the PCVD-SiN film. “LAL 500” is the“LAL 500 SA buffered hydrofluoric acid” which is solution of NH₄HF₂(7.13%) and NH₄F (15.4%), manufactured by Hashimoto Kasei Co., Ltd. Theabsolute value of the internal stress is lower than that of the siliconnitride film formed by the plasma CVD method.

Next, various physical parameters of the silicon nitride film formed bythe inventors under the conditions in table 1 are summarized in thetable 4. TABLE 4 SiN physical parameters used in the present inventionSiN film used in the parameter present invention comments specificinductive  7.0˜9.5 (preferably 7.3˜7.7) capacity refractive index1.85˜2.20 (preferably 1.90˜2.15) Wavelength of irradiated light is 632.8nm internal stress 2 × 10¹⁰ or less (dyn/cm²) (preferably 5 × 10⁸ orless) etching rate 9 or less (preferably 0.5˜3.5) LAL500, 20° C.(nm/min) Si concentration   35˜55(preferably 37˜52) RBS (atomic %) Nconcentration   45˜60(preferably 48˜56) RBS (atomic %) H concentration 1× 10²¹ or less SIMS (atoms/cm³) (preferably 5 × 10²⁰ or less) Oconcentration 5 × 10¹⁸˜5 × 10²¹ SIMS (atoms/cm³) (preferably 1 × 10¹⁹ ˜1× 10²¹) C concentration 1 × 10¹⁸˜5 × 10¹⁹ SIMS (atoms/cm³) (preferably 1× 10¹⁸ ˜2 × 10¹⁹)

The results of the SIMS (secondary ion mass spectrometry) and FT-IR, andthe transmittance, of the above silicon nitride film, are shown in FIGS.24, 25 and 26, respectively. FIG. 26 also shows the silicon nitride filmformed under the conditions of the table 2. The transmission factor isalmost comparable to that of the conventional PCVD-SiN film.

The silicon nitride film used as an inorganic insulation layer accordingto the invention preferably satisfies the parameters shown in the table4. That is, the inorganic insulation layer preferably satisfies one ofthe following conditions; (1) a silicon nitride film with etching rateof 9 nm/min or less (preferably, 0.5 to 3.5 nm/min or less), (2)hydrogen concentration of 1×10²¹ atoms/cm³ or less (preferably 5×10²⁰atoms/cm³ or less), (3) hydrogen concentration of 1×10²¹ atoms/cm³ orless (preferably 5×10²⁰ atoms/cm³ or less), and oxygen concentration offrom 5×10¹⁸ to 5×10²¹ atoms/cm³ (preferably 1×10¹⁹ to 1×10²¹ atoms/cm³),(4) etching rate of 9 nm/min or less (preferably, 0.5 to 3.5 nm/min orless), and hydrogen concentration of 1×10²³ atoms/cm³ or less(preferably 5×10²⁰ atoms/cm³ or less), and (5) etching rate of 9 nm/minor less (preferably, 0.5 to 3.5 nm/min or less), hydrogen concentrationof 1×10²¹ atoms/cm³ or less (preferably 5×10²⁰ atoms/cm³ or less),andoxygen concentration of from 5×10¹⁸ to 5×10²¹ atoms/cm³ (preferably1×10¹⁹ to 1×10²¹ atoms/cm³).

The absolute value of the internal stress may be 2×10¹⁰ dyn/cm² or less,preferably 5×10⁹ dyn/cm² or less, and more preferably 5×10⁸ dyn/cm² orless. The smaller internal stress can reduce the difference of theenergy level between the films, as well as prevent the film from peelingby the internal stress.

The silicon nitride film formed under condition shown in the table 1according to this embodiment has a distinct blocking effect against theelements belonging to Group 1 and Group 2 in the periodic table such asNa and Li, and can effectively suppress the diffusion of these mobileions. For example, a metal film made of aluminum with 0.2 to 1.5 wt %(preferably, 0.5 to 1.0 wt %) lithium added is preferred for a cathodelayer of this embodiment in terms of various physical characteristicsincluding charge injection characteristic. However, when using this typeof metal film, the lithium may diffuse and damage the performance of thetransistor. To prevent this damage, the present embodiment completelyprotects the transistor with inorganic insulation layers, so that thelithium would not diffuse to the transistor.

This is shown in the data in FIGS. 27 to 29. FIG. 27 is a diagram thatshows the change in the C-V characteristic before and after the BTstress test of the MOS structure which has a silicon nitride film(PCVD-SiN film) formed under conditions of the table 2 as a dielectric.The construction of the sample is shown in FIG. 29A, and the effect ofthe diffusion of the lithium can be determined by using Al—Li (lithiumadded aluminum) electrode as the surface electrode. As shown in FIG. 27,the BT stress test reveals that the C-V characteristic is significantlyshifted, which indicates that the lithium diffused from the surfaceelectrode has a substantial effect.

FIGS. 28A and 28B show the C-V characteristic before and after the BTstress test of the MOS structure which has a silicon nitride film formedunder conditions of the table 1 as a dielectrics. The difference in thetests of FIG. 28A and FIG. 28B is that, an Al—Si (silicon added aluminumfilm) electrode is used as a surface electrode in FIG. 28A, while anAl—Li (lithium added aluminum film) electrode is used as a surfaceelectrode in FIG. 28B. The result of FIG. 28B is the result of themeasurement of the MOS construction shown in FIG. 29B. In FIG. 29B, thefilms are laminated with thermally-oxidized film in order to reduce theeffect of difference in energy levels at the interface between thesilicon nitride film and the silicon substrate.

As can be seen from the graphs in FIGS. 28A and 28B, the C-Vcharacteristics before and after the BT stress test have similar shiftpattern, which indicates that there is no effect of lithium diffusion,that is, the silicon nitride film formed under the conditions of thetable 1 effectively serves as a blocking film.

As described, since the inorganic insulation layer used in thisinvention is extremely fine and has such high blocking effect againstmobile elements such as Na and Li, it can suppress diffusion of degassedcomponents from the planarizing film as well as suppress the diffusionof Li from the Al—Li electrode effectively. Taking advantage of theseeffects, a highly reliable display apparatus can be realized. Theinventors suppose that the inorganic insulation layer can be made finesince silicon clusters cannot easily contaminate the film, as a thinsilicon nitride film is formed on the surface of the single crystalsilicon target, then the silicon nitride film thus manufactured islaminated on the substrate.

Also, as the silicon nitride film is formed by the sputtering method atlower temperature i.e., from the ambient temperature to about 200° C.,the silicon nitride film which is used as a barrier film according tothe invention can be formed on the resin films, which is anotheradvantage over plasma CVD method. The above silicon nitride film can beused as a part of a gate insulation film when forming it by laminating.

Embodiment Embodiment 1

Next, the process of manufacturing the light emitting apparatus shown inFIG. 1 is described in detail with reference to the figures.

In FIG. 8A, the substrate 101 maybe one of a glass substrate, a quartzsubstrate or a ceramic substrate. The substrate 101 may comprise asilicon substrate, a metal substrate or a stainless substrate with aninsulation film formed thereon. A plastic substrate having heatresistance bearable to the processing temperature of the embodiment maybe used.

A first inorganic insulation layer 102 consisting of a insulation filmsuch as a silicon oxide film, a silicon nitride film or a siliconoxynitride film (SiO_(x)N_(y)) is formed on the substrate 101. A typicalexample has two-layer construction, in which the first siliconoxynitride film of 50 nm thickness is formed using SiH₄, NH₃ and N₂O asa reaction gas, and the second silicon oxynitride film of 100 nmthickness is formed on the first film, using SiH₄ and N₂O as a reactiongas.

The semiconductor layer can be obtained by crystallizing the amorphoussemiconductor film formed on the first inorganic insulation layer 102.The amorphous semiconductor film is formed with thickness of 30 to 60nm, and crystallized by heating, or irradiating laser beams. There is norestriction on the material of the amorphous semiconductor film,however, silicon or silicon germanium (Si_(1-x)Ge_(x);O<x<1.Representative value for x is 0.001 to 0.05) alloy may be preferablyused.

In a representative example, the amorphous silicon film of 54 nmthickness is formed by the plasma CVD method using SiH₄ gas. Incrystallization, a pulse oscillating or a continuous oscillating excimerlaser, or a YAG laser, a YVO₄ laser or a YLF laser which are doped withone of Cr, Nd, Er, Ho, Ce, Co, Ti or Tm can be used. When using one of aYAG laser, a YVO₄ laser or a YLF laser, the second harmonic to thefourth harmonic can be used. When using one of these lasers, the laserbeam irradiated from the laser oscillator can be linearly collected byan optical system to irradiate on the semiconductor film. The conditionof the crystallization can be selected by the operator appropriately.

For crystallization, certain metal element such as nickel which canserve as a catalyst for the crystallization of the semiconductor can beadded. An exemplary process of crystallization is; holding a solutioncontaining nickel on the amorphous silicon film, dehydrogenating (500°C. for one hour), crystallizing by furnace annealing at 550° C. for fourhours or gas heating rapid annealing at 740° C. for 180 seconds, thenirradiating the second harmonic of a continuous oscillating laserselected from an excimer laser, a YAG laser, a YVO₄ laser, or a YLFlaser, in order to improve the crystallization.

The resulting crystalline semiconductor film is etched in a desired formby photolithography using a photo mask (1) to form semiconductor layers103 to 107 separated like islands. FIG. 12 shows a top view of the pixelformation section on this point.

Also, after crystallization of the amorphous semiconductor film, thefilm can be doped with p-type impurity element in order to controlthreshold of the TFT. P-type impurity elements include the elementsbelonging to the Group 13 in the periodic table, such as boron (B),aluminum (Al) and garium (Ga).

Next, as shown in FIG. 8B, the gate insulation film 108 covering thesemiconductor layers 103 to 107 separated like islands is formed. Thegate insulation film 108 of 40 to 150 nm thickness is formed frominsulation film containing silicon by the plasma CVD method or thesputtering using inorganic insulation materials such as silicon oxide orsilicon oxynitride. This gate insulation layer can use insulation filmcontaining silicon as a single layer construction or a laminatedconstruction.

A first conductive film 10 of 30 nm thickness comprising tantalumnitride (TaN), and a second conductive film 11 of 400 nm thicknesscomprising tungsten (W) are laminated on the gate insulation film 108 inorder to form a gate electrode. Other conductive material for gateelectrode may be selected from Ta, W, Ti, Mo, Al, Cu, or an alloy or achemical compound having one of above elements as a main component.Also, a semiconductor film including a poly-crystalline silicon filmdoped with an impurity element such as phosphorous may be used.Furthermore, a combination of the first conductive film of a tantalumfilm (Ta) and the second conductive film of a W film, a combination ofthe first conductive film of a tantalum nitride (TaN) film and thesecond conductive film of a Al film, or a combination of the firstconductive film of a tantalum nitride (TaN) film, and the secondconductive film of Ti film may be also accepted.

Next, as shown in FIG. 8C, a mask 12 by which gate electrode patternsare formed by photolithography is formed by using a photo mask (2).After that, the first etching is performed with dry-etching, forexample, ICP (Inductively Coupled Plasma) etching. There is norestriction on the etching gas, however, CF₄, Cl₂ and O₂ are used foretching of W and TaN. In the first etching, predetermined biasingvoltage is applied to the substrate to make inclination angle of 15 to50 degrees on the side surface of the formed electrode patterns 13 to17. The first etching reduces the thickness of the exposed region ofsurface of the insulation film by 10 to 30 nm.

Next, anisotropic etching is performed on the W film using SF₆, Cl₂ andO₂ as etching gases, and applying predetermined biasing voltage to thesubstrate, changing the first etching condition to the second etchingcondition. The gate electrodes 110 to 113 and the wiring 109 of an inputterminal are thus formed. After that, the mask 12 is removed. The secondetching further reduces the thickness of the exposed region in thesurface of the insulation layer by about 10 to 30 nm. FIG. 13 shows atop view of the pixel formation section at this point.

After formation of the gate electrode, a first doping is performed asshown in FIG. 9A to form first n-type impurity regions in 18 to 22 onthe semiconductor layer. These first n-type impurity regions are formedin a self-aligned manner using the gate electrode as a mask. The dopingcondition can be set appropriately, using 5% PH₃ diluted with hydrogen,and injecting 6×10¹³/cm² dose at 50 kV.

Next, as shown in FIG. 9B, a mask 23 is formed by using a photo-mask (3)and a second doping is performed by photolithography. The second dopinguses 5% PH₃ diluted with hydrogen, and injects 3×10¹⁵/cm² dose at 65 kVto form second n-type impurity regions 24, 25 and 27 and third n-typeimpurity regions 26 and 28. The second n-type impurity region 24 and thethird n-type impurity region 26 formed in the semiconductor layer 103are formed in a self-aligned manner using the gate electrode as a mask.The second n-type impurity region 27 and the third n-type impurityregion 28 formed in the semiconductor layer 106 are formed in aself-aligned manner using the gate electrode as a mask. In thesemiconductor layer 105, the second n-type impurity region 25 is formedby-the mask 23.

As shown in FIG. 9C, a mask 29 is formed by using a photo-mask (4), anda third doping is performed by photolithography. The third doping uses5% B₂H₆ diluted with hydrogen, and injecting 2×10¹⁶/cm² dose at 80 kV toform a p-type impurity region 30 in the semiconductor layer 104.

As the result of the above processes, the impurity regions having eithern-type conductivity or p-type conductivity are formed on eachsemiconductor layer, respectively. As shown in FIG. 10A, in thesemiconductor layer 103, the second n-type impurity region 24 acts as asource or drain region, and the third n-type impurity region 26 acts asa LDD region. In the semiconductor layer 104, the p-type impurity region30 acts as a source or drain region. In the semiconductor layer 105, thesecond n-type impurity region 25 acts as a source or drain region, andthe first n-type impurity region 20 acts as a LDD region. In thesemiconductor layer 106, the second n-type impurity region 27 acts as asource or drain region, and the third n-type impurity region 28 acts asa LDD region.

Next, the second inorganic insulation layer 114 covering almost all thesurface is formed. The second inorganic insulation layer 114 of 100 to200 nm thickness is formed using the plasma CVD or the sputtering, withan inorganic insulation material containing silicon and hydrogen. Thepreferred example is an silicon oxynitride film of 150 nm thicknessformed by the plasma CVD.

After formation of the second inorganic insulation layer 114, eachimpurity element added to each semiconductor layer is activated.Activation is performed by heating in a furnace anneal or a clean oven.The temperature is 400 to 700° C., typically, 410 to 500° C. of nitrogenatmosphere. The impurity regions may be activated by laser anneal, orrapid thermal anneal (RTA), as well.

Next, as shown in FIG. 10B, the first organic insulation layer 115 of0.5 to 1 μm is formed on the second inorganic insulation layer 114.Thermosetting acrylic material can be used as the organic insulationlayer, which is spin-coated, then calcined at 250° C. to form planarizedfilm. On this film, the third inorganic insulation layer 116 of 50 to100 nm thickness is formed.

When forming the third inorganic insulation layer 116, the substratehaving the second inorganic insulation layer 114 formed thereon isheated at 80 to 200° C. under reduced pressure for dehydration. Anexemplary material suitable for the third inorganic insulation layer 116is silicon nitride formed by sputtering using silicon as a target.

Conditions for forming a film can be selected appropriately. Preferably,nitrogen (N₂) or mix of nitrogen and argon is applied as sputtering gasby RF power for sputtering. The substrate may be processed in atmospheretemperature, without heating. An exemplary process shows infraredabsorption spectrum of the silicon nitride film (#001) formed byapplying RF power (13.56 MHz) using silicon as a target, and using onlynitrogen gas for sputtering. The film is formed by using silicon targetboron added by 1 to 2 Ωsq., applying 0.4 Pa, 800 W RF power (13.56 MHz)and applying only nitrogen gas. The target has a diameter of 152. 4 mm.The resultant silicon nitride film has oxygen content of 20 atomic % orless, preferably 10 atomic % or less. By reducing oxygen concentration,the film can be more fine and can improve transmittance of light inshort-wavelength range.

Next, as shown in FIG. 10C, a mask pattern is formed from photo-mask (5)by photolithography. A contact hole 30 and an opening 31 of the inputterminal are formed by using a photo-mask (5), forming mask patterns byphotolithography, and dry-etching. The conditions of the dry-etching areas follows; etching the third inorganic insulation layer 116 and thesecond inorganic insulation layer 114 using CF₄, O₂ and He, then,etching the second inorganic insulation layer is performed and the gateinsulation layer using CHF₃.

After that, as shown in FIG. 11A, wirings and pixel electrodes areformed using Al, Ti, Mo or W. A photo-mask (6) is used for formingwirings. For example, a laminated film of a Ti film of 50 to 250 nmthickness and an alloy film comprising Al and Ti of 300 to 500 nmthickness may be used. The wirings 117 to 125 are thus formed.

Next, as shown in FIG. 11B, the second organic insulation layer 128 isformed. This layer is formed with an acrylic material similar to thefirst organic insulation layer 115. Then, openings are formed on thewiring 123, the connection of the anode layer 310, and the inputterminal by using a photo-mask (7). The second organic insulation layer128 is formed so as to cover the end of the wiring 123, and its sidesurface has an inclination angle of 45 degree.

The organic insulation material is hygroscopic and occludes moisture. Inorder to prevent the occlusion and release of moisture, a fourthinorganic insulation layer 129 of 10 to 100 nm thickness is formed onthe second organic insulation layer 128. The fourth inorganic insulationlayer 129 is formed of inorganic insulation material consisting of anitride. The fourth inorganic insulation layer 129 is formed from asilicon nitride film manufactured by the sputtering. The applicable filmis similar to that for the third inorganic insulation layer 116. Thefourth inorganic insulation layer 129 is formed into predeterminedpatterns by using a photo-mask (8), and covers the upper surface and theside surface of the second organic insulation layer 128, with a taperedend overlapping with the wiring 123. Thus, the fourth inorganicinsulation layer 129 is formed at the input terminal so as to cover theside surface of the opening formed in the second organic insulationlayer 128, so that it prevents moisture from penetrating from thisregion.

Next, the cathode layer 126 is formed by using calcium fluoride orcesium fluoride as a material and depositing it by vacuum deposition.Then, the organic compound layer 130 containing light emitting materialis formed. The anode layer 131 is formed on the organic compound layercontaining light emitting material, by the sputtering or resistanceheating deposition. ITO can be used as the anode layer 131. Patterns onthese layers are formed by using a metal-mask (also called ashadow-mask). The anode layer 131 is the electrode to which commonpotential is applied, and extended to the connection 310 to contact tothe wiring 120. Also, ITO film 127 is formed on the wiring at the inputterminal.

Noble gas (typically argon) is used in sputtering method. Ions ofsputtering gas are not only accelerated by sheath electric field andclash with a target, but also are accelerated by weak sheath electricfield and implanted into the organic compound layer 130 containing alight emitting material under the anode. The noble gas preventsmolecules or atoms from displacing by positioning between lattices ofthe organic compound layers and improves stability of the organiccompounds. Further, the fifth inorganic insulation layer 132 formed onthe anode 131 is formed of silicon nitride or DLC film. The ions ofnoble gas (typically argon)are accelerated by weak sheath electric fieldon the side of substrate and implanted into the organic compound layer131 under the anode 131 passing through the anode. Then, an effect ofimproving stability of the organic compound can be obtained.

Then, seal patterns are formed, a sealing plate is adhered tomanufacture a light emitting apparatus shown in FIG. 1. According to theabove processes, a light emitting apparatus can be completed with eightphoto-masks.

Embodiment 2

Next, a light emitting apparatus having different structure than that ofthe embodiment 1 will be described with reference to FIG. 14. Theprocesses from the beginning to the formation of the third inorganicinsulation layer 116 are same as those in the embodiment 1. Then, acontact hall and wirings 117 to 125 are formed.

Next, a third organic insulation layer 180 of about 1 μm thickness isformed of materials such as acrylic or polyimiide. On this third organicinsulation layer 180, a seventh inorganic insulation layer 181 is formedwith silicon nitride for the same reason as the embodiment 1.

A contact hall connecting to the wiring 123 and a cathode layer 126 areformed. A fourth organic insulation layer 182 is formed at the end ofthe cathode layer 126 and the recess of the contact hall. The surface ofthe fourth organic insulation layer 182 is covered with an eighthinorganic insulation layer 183. After that, an organic compound layer130 containing light emitting material, an anode layer 131, sealpatterns 133 are formed, and a sealing plate is adhered to complete thelight emitting apparatus.

Embodiment 3

This embodiment has a different construction than that of the embodiment1 for the pixel section, as illustrated in FIGS. 31 and 32. In thisembodiment, the processes from the beginning to the formation of thethird inorganic insulation layer 116 and wiring 123 on the thirdinorganic insulation layer 116 are same as FIG. 1.

As shown in FIG. 31A, a second organic insulation layer 180 covering theend of the wiring 123 is formed of a photosensitive, negative-typeacrylic resin. Thus, the end where the second organic insulation layer180 contacts with the wiring 123 has a inclined surface having acurvature as shown in the figure, the shape of which can be expressed byat least two curvatures R1 and R2. The center of the R1 is located abovethe wiring, while that of the R2 is located below the wiring. This shapemay vary slightly depending on the exposure, but the thickness of thefilm is 1.5 μm and the value for R1 and R2 is 0.2 to 2 μm. The inclinedsurface has continuously varying curvatures.

Then, along the inclined surface having these smooth curvatures, afourth inorganic insulation layer 129, a cathode layer 126, an organiccompound layer 130, an anode layer 131 and a fifth inorganic insulationlayer 132 are formed as shown in FIG. 31B. The shape of the section ofthis second organic insulation layer 180 has an effect of mitigatingstress (especially, a region where the wiring 123, the fourth inorganicinsulation layer 129 and the cathode layer 126 overlap), which makes itpossible to prevent the light emitting element from deteriorating fromthis end section. That is, this construction can prevent the progressivedeterioration which begins from the peripheral of the pixel then expandsto other region. In other words, a region not emitting light cannotexpand.

FIG. 32A shows an example wherein the second organic insulation layer181 is formed with a photosensitive positive-type acrylic resin insteadof the photosensitive negative-type acrylic resin. In this case, theshape of the section at the end is different. The curvature radius R3 is0.2 to 2, with its center located below the wiring 123. After formationof the second organic insulation layer 181, a fourth inorganicinsulation layer 129, a cathode layer 126, an organic compound layer130, an anode layer 131 and fifth inorganic insulation layer 132 areformed along the inclined surface having curvatures as shown in FIG.32B. The similar effect can be obtained by this construction.

This embodiment can be implemented in combination with the embodiments 1and 2.

Embodiment 4

For the embodiments 1 to 3, there is no restriction on the constructionof the organic compound layer in the light emitting element 309, sothat, any known construction is applicable. The organic compound layer130 has a light emitting layer, a positive holes injecting layer, anelectrons injecting layer, a positive holes transferring layer and anelectrons transferring layer, and may have a construction wherein theselayers are laminated, or a construction wherein a part or all of thematerials forming these layers are mixed. Particularly, the lightemitting layer, the positive holes injecting layer, the electronsinjecting layer, the positive holes transferring layer and the electronstransferring layer are included. An basic EL element has a constructionwherein an anode, a light emitting layer, a cathode are laminated inthis order. Other possible construction includes a construction whereinthe layers are laminated in an order of an anode, a positive holesinjection layer, a light emitting layer and a cathode, or an order of ananode, a positive holes injecting layer, a light emitting layer, anelectrons transferring layer and a cathode form the top.

Typically, the light emitting layer is formed using organic compound.However, it may be formed with charge injection transferring materialincluding organic compound or inorganic compound and a light emittingmaterial, it may contain one or more layers made of organic compoundselected from low molecular organic compounds, middle molecular organiccompounds, and polymer organic compounds, and the light emitting layermay be combined with inorganic compound of an electrons injectiontransferring type or a positive holes injection transferring type. Themiddle molecular organic compounds refer to organic compounds which arenot sublimatic and have molecular numbers of 20 or less, or length ofcatenated molecules does not exceed 10 μm.

The applicable light emitting materials include metal complex such astris-8-quinolinolatoaluminum complex or bis(benzoquinolinolato)berylliumcomplex as low molecular organic compounds, phenylanthracene derivative,tetraaryldiamine derivative and distyrylbenzen derivative. Using one ofthe above material as a host substance, coumarin derivative, DCM,quinacridone and rubrene may be applied. Other known materials may beapplicable as well. Polymer organic compounds includepolyparaphenylenevinylenes, polyparaphenylens, polythiophenes andpolyfluorenes, including, poly (p-phenylene vinylene): (PPV), poly(2,5-dialkoxy-1,4-phenylene vinylene):(RO-PPV), poly[2-2′-ethylhexoxy]-5-methoxy-1,4-phenylenevinylene]: (MEH-PPV), poly[2-(dialkoxyphenyl)-1,4,-phenylene vinylene]:(ROPh-PPV), poly(p-phenylene):(PPP), poly(2,5-dialkoxy-1,4-phenylene):(RO-PPP),poly(2,5-dihexoxy-1,4-phenylene)), polythiophene:(PT),poly(3-alkylthiophene):(PAT), poly(3-hexylthiophene):(PHT),poly(3-cyclohexylthiophene):(PCHT),poly(3-cyclohexyl-4-methylthiophene):(PCHMT),poly(3,4-dicyclohexylthiophene):(PDCHT),poly[3-(4-octylphenyl)-thiophene]:(POPT),poly[3-(4-octylphenyl)-2,2-bithiophene]):(PTOPT), polyfluorene:(PF),poly(9,9-dialkylfluorene):(PDAF), poly(9,9-dioctylfluorene):(PDOF).

Inorganic compounds, such as diamond-like carbon (DLC), Si, Ge andoxides and nitrides thereof, may be used for the charge injectiontransferring layer. The above materials may furthermore be added with P,B or N appropriately. Also, the charge injection transferring layer maybe oxides, nitrides or fluorides of alkali metals or alkali earthmetals, or compounds or alloys of the alkali metals or alkali earthmetals with at least Zn, Sn, V, Ru, Sm and In.

The listed materials are only examples. By using these materials,functional layers such as a positive holes injection transferring layer,a positive holes transferring layer, an electrons injection transferringlayer, an electrons transferring layer, a light emitting layer, anelectron block layer and a positive holes block layer can bemanufactured and laminated appropriately to form a light emittingelement. Also, a mixed layer or a mixed connection which combines theselayers may be formed, as well. The electroluminescence has two types oflight, i.e. a light which is emitted when the state moves back fromsinglet excited state to the ground state (fluorescence), and a lightwhich is emitted when the state moves back from triplet excited state tothe ground state (phosphorescence). The electroluminescence elementaccording to the invention can use either or both of these lights.

This embodiment can be implemented in combination with embodiments 1 to3.

Embodiment 5

The cathode layer 126 and the anode layer 131 of the light emittingelement 309 in the embodiment 1 can be reversed. In this case, thelayers are laminated in the order of the wiring 123, the anode layer126, the organic compound layer 130 and the cathode layer 131. Metalnitride (titanium nitride, for example) with a work function of 4 eV ormore, as well as ITO may be used for the anode layer 126. The cathodelayer 131 is formed from the lithium fluoride layer of 0.5 to 5 nmthickness and aluminum layer of 10 to 30 nm thickness. The aluminumlayer is formed as a translucent thin layer so that the light emittedfrom the organic compound layer 130 is irradiated through the cathodelayer 131.

This embodiment can be implemented in combination with the embodiments 1to 4.

Embodiment 6

An embodiment of manufacturing process of the semiconductor layer to beapplied to the TFT in the embodiment 1 or 2 will be described withreference to FIG. 18. In this embodiment, continuous oscillating laserbeams scan the amorphous silicon film formed on the insulation surfaceto crystallize the same.

A barrier layer 402 comprising a silicon oxynitride film of 100 nmthickness is formed on a glass substrate 401, as shown in FIG. 18A. Onthe barrier layer 402, an amorphous silicon film 403 of 54 nm thicknessis formed by the plasma CVD method.

The laser beams are continuous beams irradiated with continuousoscillation from a Nd:YVO₄ laser oscillator, and the second harmonic(532 nm) obtained by a wavelength conversion element is irradiated. Thecontinuous oscillating laser beams are collected in an oblong shape byan optical system, and by moving relative positions of the substrate 401the point from which the laser irradiate the beam 405, the amorphoussilicon film 403 is crystallized to form a crystalline silicon film 404.F20 cylindrical lens can be adopted as the optical system, whichtransforms the laser beam with a diameter of 2.5 mm into an oblong shapewith long axis of 2.5 mm and short axis of 20 μm on the irradiatedsurface.

Of course, other laser oscillator may equally be applicable. As acontinuous solid-state laser oscillator, a laser oscillator using acrystal such as YAG, YVO₄, YLF or YAlO₃, doped with Cr, Nd, Er, Ho, Ce,Co, Ti or Tm may be applicable.

When using the second harmonic (532 nm) of the Nd:YVO₄ laser oscillator,the laser beam of the wavelength is transmitted through the glasssubstrate 401 and the barrier layer 402. Therefore, the laser beam 406may be irradiated from the glass substrate 401 side, as shown in FIG.18B.

Crystallization proceeds from the area on which the laser beam 405 isirradiated, to form a crystalline silicon film 404. The laser beam maybe scanned in either one direction or backwards and forwards. Whenscanning back wards and forwards, the laser energy density may bechanged for each scanning to make gradual crystallization. The scanningmay have dehydrogenation effect as well, which is often necessary whenan amorphous silicon film is to be crystallized. In that case, the firstscanning may be performed at lower energy density, then, afterdehydrogenation, the second scanning may be performed at higher energydensity to complete the crystallization. Such process can also provide acrystalline semiconductor film in which crystal grains extend in thedirection of laser beam scanning. After these processes, semiconductorlayers are separated like islands, which can be applied to theembodiment 1.

The construction shown in this embodiment is only exemplary. Other laseroscillator, other optical system and combination thereof maybeapplicable as long as similar effect can be obtained.

Embodiment 7

An embodiment of manufacturing process of the semiconductor layer to beapplied to the TFT in the embodiment 1 or 2 will be described withreference to FIG. 19. In this embodiment, an amorphous silicon filmformed on the insulation surface is crystallized in advance, then,expanding the size of the crystal grains by continuous oscillating laserbeams.

As shown in FIG. 19A, a blocking layer 502 and an amorphous silicon film503 are formed on a glass substrate 501 as is in the embodiment 1.Nickel acetate 5 ppm solution is spin-coated to form a catalyst elementcontaining layer 504 in order to add Ni as a metal element to lower thecrystallization temperature and promote the crystallization.

The amorphous silicon film is crystallized by heating at 580° C. forfour hours, as shown in FIG. 19B. Silicide is formed and diffused in theamorphous silicon film by the action of Ni, and the crystal growssimultaneously. The resultant crystalline silicon film 506 consists ofbar-shaped or needle-shaped crystals, each of which grows in specificdirection when seen from a macroscopic viewpoint, thus the crystallinedirections are uniform.

As shown in FIG. 19C, scanning by continuous oscillating laser beam 508is performed to improve the quality of the crystallization of thecrystalline silicon film 506. By irradiating the laser beam, thecrystalline silicon film melts and re-crystallize. In thisre-crystallization, the crystal grains extend in the scanning directionof the laser beam. It is possible to suppress deposition of crystallinegrains with different crystalline grains and formation of dislocations.After these processes, semiconductor layers are separated like islands,which can be applied to the embodiment 1.

Embodiment 8

An embodiment of manufacturing process of the semiconductor layer whichcan be applied to the TFT in the embodiment 1 or 2 will be describedwith reference to FIG. 20.

As shown in FIG. 20A, a blocking layer 512 and an amorphous silicon film513 are formed on a glass substrate 511 as is in the embodiment 3. Onthe amorphous silicon film, a silicon oxide film of 100 nm thickness isformed as a mask insulation film 514 by plasma CVD, and an opening 515is provided. The nickel acetate 5 ppm solution is spin-coated in orderto add Ni as a catalyst element. Ni solution contacts with the amorphoussilicon film at the opening 515.

Next, as shown in FIG. 20B; the amorphous silicon film is crystallizedby heating at 580° C. for four hours. By the action of the catalystelement, the crystal grows from the opening 515 in a direction parallelto the surface of the substrate. The resultant crystalline silicon film517 consists of bar-shaped or needle-shaped crystals, each of whichgrows in specific direction when seen from a macroscopic viewpoint, thusthe crystalline derections are uniform. Also, it is oriented in aspecific direction.

After heating, the mask insulation film 514 is removed by etching toobtain a crystalline silicon film 517 as shown in FIG. 20C. After theseprocesses, semiconductor layers are separated like islands, which can beapplied to the embodiment 1.

Embodiment 9

In the embodiment 7 or 8, after the formation of the crystalline siliconfilm 507 or 517, a process can be added to remove the catalyst elementremaining in the film with concentration of 10¹⁹ atoms/cm³ or more, bygettering.

As shown in FIG. 21, a barrier layer 509 comprising thin silicon oxidefilm is formed on the crystalline silicon film 507, then an amorphoussilicon film added with argon or phosphorous of 1×10²⁰ atoms/cm³ to1×10²¹ atoms/cm³ is formed by the sputtering, as a gettering site 510.

The Ni which is added as a catalyst element can be segregated to thegettering site 510, by heating at 600° C. for 12 hours in a furnaceanneal, or by heating at 650 to 800° C. for 30 to 60 minutes with RTAusing lamp light or heated gas. This process reduces the concentrationof the catalyst element in the crystalline silicon film 507 to 10¹⁷atoms/cm³ or less.

The gettering under similar condition is effective for the crystallinesilicon film formed in the embodiment 2. The minute amount of the metalelement contained in the crystalline silicon film formed by irradiatinglaser beams to the amorphous silicon film can be removed by thisgettering.

Embodiment 10

FIG. 23 shows an embodiment to make a module from an EL panel in whichthe pixel section and the driving circuit section are integrally formedon the glass substrate, as shown in the embodiment 1. FIG. 23Aillustrates an EL module on which an IC containing a power supplycircuit for example is mounted on the EL panel.

In FIG. 23A, the EL panel 800 is provided with a pixel section 803having a light emitting element for each pixel, a scanning line drivingcircuit 804 for selecting a pixel in the pixel section 803, and a signalline driving circuit 805 for supplying video signals to the selectedpixel. Also, a print substrate 806 is provided with a controller 801 anda power supply circuit 802. Various signals and power supply voltageoutput from the controller 801 or a power supply circuit 802 aresupplied to the pixel section 803, the scanning line driving circuit 804and the signal line driving circuit 805 of the EL panel 800 via FPC 807.

The power supply voltage and various signals to the print substrate 806are supplied via an interface (I/F) section 808 on which a plurality ofinput terminals are disposed. In this embodiment, the print substrate806 is mounted on the EL panel 800 using FPC, but the invention is notlimited to this particular construction. The controller 801 and thepower supply circuit 802 may be mounted directly on the EL panel 800using COG (Chip on Glass) technique. In the print substrate 806, noisesmay be introduced in the power supply voltage or the signals due to thecapacity formed in the wirings or the resistance of the wirings itself,which may prevent sharp rising edge of a signal. In order to avoid thisproblem, the print substrate 806 may be provided with elements such as acapacitor or a buffer, to prevent noises on the power supply voltage orsignals, and to keep sharp rising edge of the signal.

FIG. 23B is a block diagram which shows a construction of the printsubstrate 806. The various signals and the power supply voltage suppliedto the interface 808 are supplied to the controller 801 and the powersupply voltage 802. The controller 801 has an A/D converter 809, a PLL(phase locked loop) 810, a control signal generator 811 and SRAMs(Static Random Access Memory) 812 and 813. Although this embodiment usesSRAMS, SDRAMs or DRAMs (Dynamic Random Access Memory, provided that itcan read/write data at high speed) may be used as well.

The video signals supplied via the interface 808 are converted fromparallel form to serial form by the A/D converter 809, and input intothe control signal generator 811, as video signals each of whichcorresponds to R, G, B colors, respectively. Based on the signalssupplied via the interface 808, the A/D converter 809 generates Hsyncsignals, Vsync signals, clock signal CLKs, and Volts alternating current[VAC], all of which are input into the control signal generator 811.

The phase locked loop 810 is able to make the phases of the frequenciesof the various signals supplied via the interface 808 to be matched tothat of the operating frequency of the control signal generator 811. Theoperating frequency of the control signal generator 811 is not alwayssame as the frequency of the various signals supplied via the interface808, so that the phase locked loop 810 adjusts the operating frequencyof the control signal generator 811 to make the frequency synchronizedwith that of the signals. The video signal which is input into thecontrol signal generator 811 is temporarily written and stored in theSRAMs 812 and 813. From all of the video signal bits stored in the SRAM812, the control signal generator 811 reads the video signalcorresponding to the all pixels by one bit at a time, and supplies thebit to the signal line driving circuit 805 of the EL panel 800.

The control signal generator 811 supplies information related to theperiod during which the light emitting element emits light for each bit,to the scanning line driving circuit 804 of the EL panel 800. The powersupply circuit 802 supplies the predetermined power supply voltage tothe signal line driving circuit 805, the scanning line driving circuit804 and the pixel section 803, of the EL panel 800.

FIG. 22 shows examples of electronic apparatuses in which the above ELmodule may be incorporated.

FIG. 22A is an example of a television receiver in which the EL moduleis incorporated, comprising a casing 3001, a support 3002 and a displayunit 3003. The TFT substrate manufactured according to the invention isadopted in the display unit 3003 to complete the television receiver.

FIG. 22B is an example of a video camera in which the EL module isincorporated, comprising a body 3011, a display unit 3012, a sound input3013, an operating switch 3014, a battery 3015 and an image receivingsection 3016. The TFT substrate manufactured according to the inventionis adopted in the display unit 3012 to complete the video camera.

FIG. 22C is an example of a notebook-type personal computer in which theEL module is incorporated, comprising a body 3021, a casing 3022, adisplay unit 3023 and a keyboard 3024. The TFT substrate manufacturedaccording to the invention is adopted in the display unit 3023 tocomplete the personal computer.

FIG. 22D is an example of PDA (Personal Digital Assistant) in which theEL module is incorporated, comprising a body 3031, a stylus 3032, adisplay unit 3033, an operating button 3034 and an external interface3035. The TFT substrate manufactured according to the invention isadopted in the display unit 3033 to complete the PDA.

FIG. 22E is an example of an car audio system in which the EL module isincorporated, comprising a body 3041, a display unit 3042 and operatingswitches 3043 and 3044. The TFT substrate manufactured according to theinvention is adopted in the display unit 3042 to complete the car audiosystem.

FIG. 22F is an example of a digital camera in which the EL module isincorporated, comprising a body 3051, a display unit (A) 3052, aneyepiece 3053, an operating switch 3054, a display unit (B) 3055 and abattery 3056. The TFT substrates manufactured according to the inventionare adopted to the displays (A) 3052 and (B) 3055 to complete thedigital camera.

FIG. 22G is an example of a mobile telephone in which the El module isincorporated, comprising a body 3061, a voice output section 3062, avoice input section 3063, a display unit 3064, an operating switch 3065and an antenna 3066. The TFT substrate manufactured according to theinvention is adopted to the display unit 3064 to complete the mobiletelephone.

The application of the invention is not limited to the apparatuses shownin this figure. Instead, it can be adopted in a variety of electronics.

According to the invention, the semiconductor film, the gate insulationfilm and the gate electrode, which are the main components of a TFT, aresurrounded by inorganic insulation materials over their upper surfacesand under their lower surfaces to prevent contamination by alkali metalsand organic materials. The inorganic insulation material is selectedfrom a group consisting of silicon nitride, silicon oxynitride, aluminumoxynitride, aluminum oxide and aluminum nitride. The organic lightemitting element contains alkali metal in its part, and surrounded byinorganic insulation material to realize a construction which canprevent penetration of oxygen or moisture from external world. Theinorganic insulation material is selected from a group consisting ofsilicon nitride, silicon oxynitride, aluminum oxynitride, aluminumoxide, aluminum nitride and DLC. This construction can improve thereliability of the light emitting apparatus.

1. A light emitting device comprising: a thin film transistor over aninsulating surface comprising: a semiconductor layer; a gate insulationfilm; and a gate electrode; a first inorganic insulation layer under thesemiconductor layer; a second inorganic insulation layer over the gateelectrode; a first organic insulation layer over the second inorganicinsulation layer; a third inorganic insulation layer over the firstorganic insulation layer; a wiring layer extending over the thirdinorganic insulation layer; a second organic insulation layeroverlapping with an end of the wiring layer, the second organicinsulation layer having an inclined surface with continuously varyingcurvatures; a fourth inorganic insulation layer formed over an uppersurface and a side surface of the second organic insulation layer, thefourth inorganic insulation layer having an opening over the wiringlayer; a cathode layer formed over the wiring layer, the cathode layerhaving an end overlapping with the fourth inorganic insulation layer; alight emitting layer comprising an organic material formed over thecathode layer and the fourth inorganic insulation layer; an anode layerformed over the light emitting layer comprising an organic material; anda fifth inorganic insulation layer formed over the anode layer, whereinthe light emitted from the light emitting material is visible throughthe fifth inorganic insulation layer and the anode, and wherein each ofthe third inorganic insulation layer and the fourth inorganic insulationlayer comprises a material selected from the group consisting of siliconnitride and aluminum nitride.